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| Icaronycteris gunnelli, paratype. Image credit: Rietbergen et al., doi: 10.1371/journal.pone.0283505. |
Scientists have identified a new species of bat, which is the oldest bat skeleton found in the world. This discovery has helped to fill in the gaps in the fossil record of these flying creatures and given researchers new insights into how they evolved.
The two skeletons were found in an old lakebed in the southwest of Wyoming, according to the study.
The site contains the remains of an entire ecosystem from around 52 million years ago, including a subtropical lake and surrounding forest.
The newly found bat is called Icaronycteris gunnelli and it was very small, weighing only around 25 grams, which is equivalent to five marbles. Despite its small size, it had already evolved the ability to fly and was likely able to use echolocation.
The bat probably lived in the trees around the lake and hunted insects by flying over the water. The study, which describes the new species, was led by Tim Rietbergen, an evolutionary biologist at the Naturalis Biodiversity Centre in the Netherlands, and has been published in the scientific journal PLOS ONE.
Bats belonged to the Eocene epoch period
The skeletons found in Wyoming showed that they belonged to the early Eocene epoch. During this time, the Earth’s temperature was getting warmer, and animals, insects, and plants were quickly spreading and diversifying.
The bats discovered in Fossil Lake are similar to the bats we have today, with long fingers used to hold their wing membranes.
Matthew Jones, a paleontologist from Arizona State University and one of the study’s authors, believes that bats came from small, tree-dwelling mammals that fed on insects.
However, there are many different types of small mammals, and we are not sure which ones are related to bats. Most of these mammals are only known from fragments of their teeth and jaws.
Similar to modern bats, yet different
Two skeletons resemble modern bats; however, there are small differences between the newly discovered bats and the bats we know today. The bones of the newly discovered bats are much stronger and more robust, especially in their hind limbs, explained Rietbergen, the lead author of the study.
Nowadays, most bats have lightweight and slender bones, which help them fly better. The thicker hind limbs of the newly discovered bats could indicate that they have inherited some of the characteristics of their ancestors. So, it is possible that these bats had stronger legs to climb trees.
Furthermore, the newly discovered bat species had a claw on its index finger in addition to the thumb claw. Most bats today only have a thumb claw which helps them to hang upside down while sleeping
Moreover, this new information suggests that the bats from this period could be the final phase of a transformation from climbers to expert fliers.
Sources:
T.B. Rietbergen et al. 2023 .The oldest known bat skeletons and their implications for Eocene chiropteran diversification. PLoS ONE 18 (4): e0283505; doi: 10.1371/journal.pone.0283505
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